A screen used for projection of a slide or OHP, or, for projection of a movie or video is generally a lamination of a dark backing sheet and a white polyvinyl chloride (PVC) film. Conventional screens have low reflectivities and therefore dark projected images, so that the projected images cannot be watched except in a dark room. In addition, the conventional screens have low diffusing powers, so that the projected images cannot be watched except within a limited range of angle to the screen surface.
There is a screen in which glass beads are bonded to the PVC film to enhance the reflectivity and the diffusing power. Such a screen, however, has unevenness on its surface and is easily contaminated. Therefore, the glass beads are readily scraped off when the contaminants are wiped off from the surface thereof, which is a defect of such a screen. If such a screen is used as a screen of wind-up type, the glass beads will gradually drop off while the screen is wound and unwound many times, which is also a problem.
There is proposed ( in Japanese Laid-open Utility Model Publication No. Sho 64-40835) a screen comprising the dark backing sheet and the white PVC film as described above, in which a metallized layer is provided as a reflection layer on the white PVC film, in which a translucent PVC film containing a pearl pigment is laminated thereon, and in which a specific emboss is provided on the outer surface thereof.
A screen having a reflection layer of metal has a too high light reflectivity and too many components of specular reflection (where incidence angle =reflection angle), so that a halation is caused to present a dull image projected. In addition, while a plastic sheet (mainly a polyester sheet) must be used with a strong adhesivity to the metallized layer in order to form the metallized layer as a reflection layer, there is a defect in that such a plastic sheet is likely to have creases. In other words, there remain folds caused upon transfer or wind-up of the screen, and the high reflectivity makes the folds outstanding. These problems are serious if a screen should be of a big picture plane, for example, of 100 inches.